Field
Embodiments of the present disclosure generally relate to methods and apparatus for in-situ cleaning a plasma processing chamber utilized to etch a substrate. Particularly, embodiments of the present disclosure relate to methods and apparatus for in-situ chamber cleaning a plasma processing chamber utilized to etch a substrate.
Description of the Related Art
The fabrication of microelectronics or integrated circuit devices typically involves a complicated process sequence requiring hundreds of individual steps performed on semiconductive, dielectric and conductive substrates. Examples of these process steps include oxidation, diffusion, ion implantation, thin film deposition, cleaning, etching and lithography. Using lithography and etching (often referred to as pattern transfer steps) processes, a desired pattern is first transferred to a photosensitive material layer, e.g., a photoresist, and then to the underlying material layer during the subsequent etching process. In the lithographic step, a blanket photoresist layer is exposed to a radiation source through a reticle or photomask, which is typically formed in a metal-containing layer supported on a glass or quartz substrate, containing a pattern so that an image of the pattern is formed in the photoresist. By developing the photoresist in a suitable chemical solution, portions of the photoresist are removed, thus resulting in a patterned photoresist layer. With this photoresist pattern acting as a mask, the underlying material layer is exposed to a reactive environment, e.g., using dry etching, which results in the pattern being transferred to the underlying material layer.
An example of a commercially available photomask etch equipment suitable for use in advanced device fabrication is the TETRA® Photomask Etch System, available from Applied Materials, Inc., of Santa Clara, Calif. The metal-containing layers patterned by a plasma processing such as photomask plasma etching process offers good critical dimension control than conventional wet chemical etching in the fabrication of microelectronic devices. Plasma etching technology is widely applied in the semiconductor and thin film transistor-liquid crystal display (TFT-LCD) industry.
During dry etching photomasks in the plasma chamber, materials such as chromium (Cr), MoSi, quartz, SiON or Ta-based compounds may be deposited to form layers of etching by-products. After the etching process, etching by-products may accumulate and deposit on the inner wall of the chamber. For example, when dry etching a Cr layer disposed on the substrate, the etch by-products may predominantly be photoresist with Cr containing materials. Alternatively, when dry etching Ta, the etch by-products may predominantly be photoresist with Ta containing materials. When the deposited etch by-products reach a certain thickness, the by-products may peel off from the inner wall of the plasma chamber and contaminate the photomask by falling onto the photomask substrate, causing irreparable defects to the photomask.
Accordingly, in order to maintain cleanliness of the processing chamber, a periodic cleaning process is performed to remove the by-products from the processing chamber. By-products deposited on chamber components or chamber inner walls are periodically cleaned typically with highly reactive chemicals. Attack from the reactive species during processing and cleaning reduces the lifespan of the chamber components and increase service frequency. Additionally, flakes from the eroded parts of the chamber component, such as aluminum fluoride (AlF), may become a source of particulate contamination during substrate processing. Accordingly, it is important to remove the deposited etching by-products and clean the chamber components and inner walls without damaging the chamber components and inner walls.
Therefore, there is a need for an improved process for cleaning plasma chamber after etching for a semiconductor substrate or photomask fabrication.